Originally, the B-2's primary purpose was to carry nuclear bombs into the Soviet Union in the event of war. With the collapse of the Soviet Union in 1991, the military redefined the B-2's role somewhat. It is now classified as a multi-role bomber -- it is designed to carry conventional bombs in addition to nuclear munitions.
The B-2 packs two rotary launchers, housed in the center of the craft. When the mission commander is ready to fire, he or she sends a signal to the onboard computer. The computer opens the bomb bay doors, rotates the launcher to position the correct bomb and then releases that bomb.
The launchers carry conventional gravity bombs -- "dumb" bombs that simply fall on their target -- as well as precision guided bombs that seek out their target. The plane can carry about 40,000 pounds of munitions.
The B-2's precision guided bombs are actually "dumb" munitions with a separate guidance system attached. This guidance kit, known as Joint Direct Attack Munition (JDAM), includes adjustable tail fins, a control computer, an inertial guidance system, and a GPS receiver. The B-2 uses its own GPS receiver to pinpoint targets. Once the crew has located its target, they feed the target's GPS coordinates to the JDAM and release the bomb.
In the air, the JDAM's GPS receiver processes signals from GPS satellites to keep track of its own position, while the inertial guidance system tracks the bomb's change in position. The control computer adjusts the JDAM's flight fins to guide the bomb to the intended target. This precise targeting system allows the B-2 to drop its bombs and make a quick escape. The bomb works fine even in bad weather, because the JDAM only needs to receive satellite signals to find its target. It doesn't have to see anything on the ground at all. (See How Smart Bombs Work for more information.)
Because of its high cost and relative inexperience in the field, the B-2 is a fairly controversial weapon. While some analysts hold it up as the pinnacle of military aircraft, others say the plane has severe limitations, such as its stealth capabilities' high sensitivity to bad weather. But just about everybody agrees it is a pivotal development in the evolution of aeronautic technology. It is certainly an amazing machine.
For much more information about the B-2, including the fascinating story of its invention, check out the links on the next page.